1. Field of the Invention
The present invention relates to a pattern writing system and a pattern monitoring method for a pattern writing apparatus, for example, a pattern writing system that writes a pattern on a target object by use of an electron beam and a method of monitoring parameters set in the system.
2. Related Art
A lithography technique that leads development of micropatterning of a semiconductor device is a very important process that generates a pattern in semiconductor manufacturing processes. In recent years, with an increase in LSI integration density, the circuit line width required for a semiconductor device is further miniaturized every year. A high-precision original pattern (also called a reticule or a mask) is necessary in order to form the desired circuit pattern on such a semiconductor device. In such cases, an electron beam pattern writing technique essentially has an excellent resolution and is used in production of high-precision original patterns.
FIG. 5 is a conceptual diagram that explains the operation of a conventional variable-shaped electron beam photolithography apparatus.
The operation of the variable-shaped electron beam (EB) photolithography apparatus will be described below. In the first aperture plate 410, an oblong (e.g. rectangular) opening 411 is formed to shape an electron beam 330. In the second aperture plate 420, a variable-shaped opening 421 is formed to shape the electron beam 330 passing through the opening 411 of the first aperture plate 410 into the desired oblong shape. The electron beam 330 irradiated from the charged particle source 430 and passing through the opening 411 of the first aperture plate 410 is deflected by a deflector, passes through a part of the variable-shaped opening 421 of the second aperture plate 420, and is irradiated on a target object 340 placed on a stage continuously moving in one predetermined direction (e.g. direction X). More specifically, an oblong shape that can pass through both the opening 411 of the first aperture plate 410 and the variable-shaped opening 421 of the second aperture plate 420 is written in a pattern writing region on the target object 340 that is placed on the stage and continuously moving in the direction X. The scheme that causes a beam to pass through the opening 411 of the first aperture plate 410 and the variable-shaped opening 421 of the second aperture plate 420 to form an arbitrary shape is called a variable-shaping scheme (for an example, see Japanese Unexamined Patent Publication No. 2007-294562).
In this case, in a pattern writing apparatus typified by an electron beam photolithography apparatus, a very large number of pieces of apparatus application information (parameters) are prepared in order to variably apply the apparatus. Quality management of products produced by the pattern writing requires change management of these parameters. However, it is technically difficult for the owner (manager) himself/herself to manage the parameters of the pattern writing apparatus that have been developed into various forms on an apparatus. This is because when the pattern writing apparatus goes online, the apparatus parameters can be remotely changed to make it possible to designate changes at any time. Furthermore, as described below, parameter management is difficult.
FIG. 6 is a conceptual diagram showing a sample configuration of a pattern writing system.
In this case, after parameters designated by personal computers (PC) 552 and 554 of users A and B or other such parameters to be changed are stored in database 540 or other such databases first, the settings of devices 522 and 524, which control a pattern writing unit 510 through interface (I/F) circuits 534 and 536, are changed. The devices 522 and 524 the parameters, of which those that are set frequently have different communication specifications. For this reason, in the configuration, the devices 522 and 524 the parameters set cannot be easily directly accessed from a management PC 560. In a conventional technique, in order to check whether the parameters differ from those of the reference 564, the apparatus owner checks the parameters stored in the database 540 by using a management PC 560. However, even though the parameters are stored in the database 540 or other similar locations, a slight time lag occurs until the parameters are set in the devices 522 and 524 in the actual pattern writing apparatus. As a result, the contents in the database 540 may differ from those set in the devices 522 and 524 of the actual device. For this reason, even though the parameters of the reference are matched with the parameters in the database, the contents of the reference 564 may differ from those set in the devices 522 and 524. In this manner, even though the parameters of the reference are compared with the parameters in the database, pattern writing that is not based on the assumption that settings in the real device are different may be at a disadvantage when performed.
As described above, when it cannot be predicted at what time settings will be changed nor who will change them, the content in the database may differ from that set in the actual device, and parameter management by the apparatus owner is very difficult.
As described above, even though the parameters stored in the database are checked via a management PC, the contents of the database and the contents set in the actual device may be different an unexpected pattern writing may be at a disadvantage when performed. In particular, with micropatterning of a pattern and the complexity of the pattern writing apparatus, this problem is very serious in regard to the management of enormous numbers of parameters.